Growing pollen tubes possess a constitutive alkaline band in the clear zone and a growth-dependent acidic tip.
Growing pollen tubes possess a constitutive alkaline band in the clear zone and a growth-dependent acidic tip.
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DOI：
10.1083/jcb.144.3.483
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发表时间：
1999-02-08
期刊：
影响因子：
--
通讯作者：
Hepler PK
中科院分区：
文献类型：
--
作者：
Feijó JA;Sainhas J;Hackett GR;Kunkel JG;Hepler PK
用质子选择振动电极探测胞外电流，用2′，7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein(BCECF)-葡聚糖为指示剂的比率广场荧光显微镜成像胞内pH，研究了与花粉管生长相关的质子(H+)的分布和活性。细胞内图像显示，百合花粉管在透明带的底部有一个构成碱性带，在最顶端有一个酸性结构域。细胞外观察显示，在花粉管的最顶端有质子流入，而在与碱性带位置相对应的区域有质子流出。检测细胞内pH梯度的能力强烈依赖于细胞质中外源缓冲液的浓度。因此，即使是指示剂染料，如果以估计为1.0μM或更高的水平引入，也会通过穿梭缓冲来消散梯度。顶端酸性结构域与生长过程密切相关，因此可能在促进囊泡运动和胞吐方面发挥直接作用。碱性带与透明带底部反向喷泉的位置相关，并可能通过调节pH敏感的肌动蛋白结合蛋白参与肌动蛋白细丝形成的调节。这些研究不仅证明了质子梯度的存在，而且它们可能与极化花粉管的生长密切相关。
Using both the proton selective vibrating electrode to probe the extracellular currents and ratiometric wide-field fluorescence microscopy with the indicator 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran to image the intracellular pH, we have examined the distribution and activity of protons (H+) associated with pollen tube growth. The intracellular images reveal that lily pollen tubes possess a constitutive alkaline band at the base of the clear zone and an acidic domain at the extreme apex. The extracellular observations, in close agreement, show a proton influx at the extreme apex of the pollen tube and an efflux in the region that corresponds to the position of the alkaline band. The ability to detect the intracellular pH gradient is strongly dependent on the concentration of exogenous buffers in the cytoplasm. Thus, even the indicator dye, if introduced at levels estimated to be of 1.0 μM or greater, will dissipate the gradient, possibly through shuttle buffering. The apical acidic domain correlates closely with the process of growth, and thus may play a direct role, possibly in facilitating vesicle movement and exocytosis. The alkaline band correlates with the position of the reverse fountain streaming at the base of the clear zone, and may participate in the regulation of actin filament formation through the modulation of pH-sensitive actin binding proteins. These studies not only demonstrate that proton gradients exist, but that they may be intimately associated with polarized pollen tube growth.
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影响因子：
56.9
作者：
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通讯作者：
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